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VERTEBRATE ZOOLOGY 



FIG. 161. Cleavage of hen's egg. A, first cleavage furrow (x 14). The egg 

 came from the lower end of the oviduct. B, Four-celled stage (x 17); from the 

 uterus; C, Ten central and eleven marginal cells (x about 16); D, nine central and 

 sixteen marginal cells (x about 16); E, late cleavage stage (x about 22). (From 

 Lillie's " Development of the Chick," after Kolliker.) 



